1. Field of the Invention
The present invention relates to disk drive suspensions, and more particularly, to disk drive suspensions having controlled 1st and 2nd torsion gains through variations in edge rail geometry. A disk drive suspension is provided having a beam portion with edge rails extending along its edge regions and a plane of excitation extending between the suspension base portion and the suspension dimple. The edge rails are locally varied substantially identically between lesser and greater heights along their lengths to control 1st and 2nd torsion characteristics. A beam portion central region increasingly extends above or below the plane of excitation in inverse response to the edge rails increasingly or decreasingly extending above the plane of excitation. The inverse extending relation of the beam portion central region and the rail heights relative to the plane of excitation tends to offset in at least part changes in the balance of the suspension upper and lower inertia components from changes in the geometry of said suspension. Control of 1st and 2nd torsion characteristics is achieved beyond that available by spring portion modification, and inertia component balance above and below the plane of excitation is maintained by complementary, offsetting deflections of the beam portion.
2. Background Art
A beam portion carrying a flexure and slider in operative association with a disk, is arranged to apply vertical force on the slider to counteract the force on the slider developed by an air bearing generated at the surface of the disk. A predetermined flying height allows a magnetic head adjacent a trailing edge of the slider to read and write on the disk. The suspension carries the slider from disk track to disk track to write magnetic information, and to retrieve or read magnetic information from a written track, in an action termed “seeking.” Seeking is done at certain velocities and with certain accelerations of the suspension and slider. Dynamic characteristics of the suspension beam can introduce some errors in the finding of, and settling opposite, a track. Suspensions also tend to vibrate while seeking, in bending, torsion and sway modes and in any direction in space. For each mode of vibrations there is a resonance gain associated with the vibration frequency.